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path: root/drivers/mtd/lpddr/lpddr_cmds.c
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/*
 * LPDDR flash memory device operations. This module provides read, write,
 * erase, lock/unlock support for LPDDR flash memories
 * (C) 2008 Korolev Alexey <akorolev@infradead.org>
 * (C) 2008 Vasiliy Leonenko <vasiliy.leonenko@gmail.com>
 * Many thanks to Roman Borisov for initial enabling
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 * TODO:
 * Implement VPP management
 * Implement XIP support
 * Implement OTP support
 */
#include <linux/mtd/pfow.h>
#include <linux/mtd/qinfo.h>
#include <linux/slab.h>
#include <linux/module.h>

static int lpddr_read(struct mtd_info *mtd, loff_t adr, size_t len,
					size_t *retlen, u_char *buf);
static int lpddr_write_buffers(struct mtd_info *mtd, loff_t to,
				size_t len, size_t *retlen, const u_char *buf);
static int lpddr_writev(struct mtd_info *mtd, const struct kvec *vecs,
				unsigned long count, loff_t to, size_t *retlen);
static int lpddr_erase(struct mtd_info *mtd, struct erase_info *instr);
static int lpddr_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len);
static int lpddr_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len);
static int lpddr_point(struct mtd_info *mtd, loff_t adr, size_t len,
			size_t *retlen, void **mtdbuf, resource_size_t *phys);
static int lpddr_unpoint(struct mtd_info *mtd, loff_t adr, size_t len);
static int get_chip(struct map_info *map, struct flchip *chip, int mode);
static int chip_ready(struct map_info *map, struct flchip *chip, int mode);
static void put_chip(struct map_info *map, struct flchip *chip);

struct mtd_info *lpddr_cmdset(struct map_info *map)
{
	struct lpddr_private *lpddr = map->fldrv_priv;
	struct flchip_shared *shared;
	struct flchip *chip;
	struct mtd_info *mtd;
	int numchips;
	int i, j;

	mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
	if (!mtd) {
		printk(KERN_ERR "Failed to allocate memory for MTD device\n");
		return NULL;
	}
	mtd->priv = map;
	mtd->type = MTD_NORFLASH;

	/* Fill in the default mtd operations */
	mtd->_read = lpddr_read;
	mtd->type = MTD_NORFLASH;
	mtd->flags = MTD_CAP_NORFLASH;
	mtd->flags &= ~MTD_BIT_WRITEABLE;
	mtd->_erase = lpddr_erase;
	mtd->_write = lpddr_write_buffers;
	mtd->_writev = lpddr_writev;
	mtd->_lock = lpddr_lock;
	mtd->_unlock = lpddr_unlock;
	if (map_is_linear(map)) {
		mtd->_point = lpddr_point;
		mtd->_unpoint = lpddr_unpoint;
	}
	mtd->size = 1 << lpddr->qinfo->DevSizeShift;
	mtd->erasesize = 1 << lpddr->qinfo->UniformBlockSizeShift;
	mtd->writesize = 1 << lpddr->qinfo->BufSizeShift;

	shared = kmalloc(sizeof(struct flchip_shared) * lpddr->numchips,
						GFP_KERNEL);
	if (!shared) {
		kfree(lpddr);
		kfree(mtd);
		return NULL;
	}

	chip = &lpddr->chips[0];
	numchips = lpddr->numchips / lpddr->qinfo->HWPartsNum;
	for (i = 0; i < numchips; i++) {
		shared[i].writing = shared[i].erasing = NULL;
		mutex_init(&shared[i].lock);
		for (j = 0; j < lpddr->qinfo->HWPartsNum; j++) {
			*chip = lpddr->chips[i];
			chip->start += j << lpddr->chipshift;
			chip->oldstate = chip->state = FL_READY;
			chip->priv = &shared[i];
			/* those should be reset too since
			   they create memory references. */
			init_waitqueue_head(&chip->wq);
			mutex_init(&chip->mutex);
			chip++;
		}
	}

	return mtd;
}
EXPORT_SYMBOL(lpddr_cmdset);

static int wait_for_ready(struct map_info *map, struct flchip *chip,
		unsigned int chip_op_time)
{
	unsigned int timeo, reset_timeo, sleep_time;
	unsigned int dsr;
	flstate_t chip_state = chip->state;
	int ret = 0;

	/* set our timeout to 8 times the expected delay */
	timeo = chip_op_time * 8;
	if (!timeo)
		timeo = 500000;
	reset_timeo = timeo;
	sleep_time = chip_op_time / 2;

	for (;;) {
		dsr = CMDVAL(map_read(map, map->pfow_base + PFOW_DSR));
		if (dsr & DSR_READY_STATUS)
			break;
		if (!timeo) {
			printk(KERN_ERR "%s: Flash timeout error state %d \n",
							map->name, chip_state);
			ret = -ETIME;
			break;
		}

		/* OK Still waiting. Drop the lock, wait a while and retry. */
		mutex_unlock(&chip->mutex);
		if (sleep_time >= 1000000/HZ) {
			/*
			 * Half of the normal delay still remaining
			 * can be performed with a sleeping delay instead
			 * of busy waiting.
			 */
			msleep(sleep_time/1000);
			timeo -= sleep_time;
			sleep_time = 1000000/HZ;
		} else {
			udelay(1);
			cond_resched();
			timeo--;
		}
		mutex_lock(&chip->mutex);

		while (chip->state != chip_state) {
			/* Someone's suspended the operation: sleep */
			DECLARE_WAITQUEUE(wait, current);
			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&chip->wq, &wait);
			mutex_unlock(&chip->mutex);
			schedule();
			remove_wait_queue(&chip->wq, &wait);
			mutex_lock(&chip->mutex);
		}
		if (chip->erase_suspended || chip->write_suspended)  {
			/* Suspend has occurred while sleep: reset timeout */
			timeo = reset_timeo;
			chip->erase_suspended = chip->write_suspended = 0;
		}
	}
	/* check status for errors */
	if (dsr & DSR_ERR) {
		/* Clear DSR*/
		map_write(map, CMD(~(DSR_ERR)), map->pfow_base + PFOW_DSR);
		printk(KERN_WARNING"%s: Bad status on wait: 0x%x \n",
				map->name, dsr);
		print_drs_error(dsr);
		ret = -EIO;
	}
	chip->state = FL_READY;
	return ret;
}

static int get_chip(struct map_info *map, struct flchip *chip, int mode)
{
	int ret;
	DECLARE_WAITQUEUE(wait, current);

 retry:
	if (chip->priv && (mode == FL_WRITING || mode == FL_ERASING)
		&& chip->state != FL_SYNCING) {
		/*
		 * OK. We have possibility for contension on the write/erase
		 * operations which are global to the real chip and not per
		 * partition.  So let's fight it over in the partition which
		 * currently has authority on the operation.
		 *
		 * The rules are as follows:
		 *
		 * - any write operation must own shared->writing.
		 *
		 * - any erase operation must own _both_ shared->writing and
		 *   shared->erasing.
		 *
		 * - contension arbitration is handled in the owner's context.
		 *
		 * The 'shared' struct can be read and/or written only when
		 * its lock is taken.
		 */
		struct flchip_shared *shared = chip->priv;
		struct flchip *contender;
		mutex_lock(&shared->lock);
		contender = shared->writing;
		if (contender && contender != chip) {
			/*
			 * The engine to perform desired operation on this
			 * partition is already in use by someone else.
			 * Let's fight over it in the context of the chip
			 * currently using it.  If it is possible to suspend,
			 * that other partition will do just that, otherwise
			 * it'll happily send us to sleep.  In any case, when
			 * get_chip returns success we're clear to go ahead.
			 */
			ret = mutex_trylock(&contender->mutex);
			mutex_unlock(&shared->lock);
			if (!ret)
				goto retry;
			mutex_unlock(&chip->mutex);
			ret = chip_ready(map, contender, mode);
			mutex_lock(&chip->mutex);

			if (ret == -EAGAIN) {
				mutex_unlock(&contender->mutex);
				goto retry;
			}
			if (ret) {
				mutex_unlock(&contender->mutex);
				return ret;
			}
			mutex_lock(&shared->lock);

			/* We should not own chip if it is already in FL_SYNCING
			 * state. Put contender and retry. */
			if (chip->state == FL_SYNCING) {
				put_chip(map, contender);
				mutex_unlock(&contender->mutex);
				goto retry;
			}
			mutex_unlock(&contender->mutex);
		}

		/* Check if we have suspended erase on this chip.
		   Must sleep in such a case. */
		if (mode == FL_ERASING && shared->erasing
		    && shared->erasing->oldstate == FL_ERASING) {
			mutex_unlock(&shared->lock);
			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&chip->wq, &wait);
			mutex_unlock(&chip->mutex);
			schedule();
			remove_wait_queue(&chip->wq, &wait);
			mutex_lock(&chip->mutex);
			goto retry;
		}

		/* We now own it */
		shared->writing = chip;
		if (mode == FL_ERASING)
			shared->erasing = chip;
		mutex_unlock(&shared->lock);
	}

	ret = chip_ready(map, chip, mode);
	if (ret == -EAGAIN)
		goto retry;

	return ret;
}

static int chip_ready(struct map_info *map, struct flchip *chip, int mode)
{
	struct lpddr_private *lpddr = map->fldrv_priv;
	int ret = 0;
	DECLARE_WAITQUEUE(wait, current);

	/* Prevent setting state FL_SYNCING for chip in suspended state. */
	if (FL_SYNCING == mode && FL_READY != chip->oldstate)
		goto sleep;

	switch (chip->state) {
	case FL_READY:
	case FL_JEDEC_QUERY:
		return 0;

	case FL_ERASING:
		if (!lpddr->qinfo->SuspEraseSupp ||
			!(mode == FL_READY || mode == FL_POINT))
			goto sleep;

		map_write(map, CMD(LPDDR_SUSPEND),
			map->pfow_base + PFOW_PROGRAM_ERASE_SUSPEND);
		chip->oldstate = FL_ERASING;
		chip->state = FL_ERASE_SUSPENDING;
		ret = wait_for_ready(map, chip, 0);
		if (ret) {
			/* Oops. something got wrong. */
			/* Resume and pretend we weren't here.  */
			put_chip(map, chip);
			printk(KERN_ERR "%s: suspend operation failed."
					"State may be wrong \n", map->name);
			return -EIO;
		}
		chip->erase_suspended = 1;
		chip->state = FL_READY;
		return 0;
		/* Erase suspend */
	case FL_POINT:
		/* Only if there's no operation suspended... */
		if (mode == FL_READY && chip->oldstate == FL_READY)
			return 0;

	default:
sleep:
		set_current_state(TASK_UNINTERRUPTIBLE);
		add_wait_queue(&chip->wq, &wait);
		mutex_unlock(&chip->mutex);
		schedule();
		remove_wait_queue(&chip->wq, &wait);
		mutex_lock(&chip->mutex);
		return -EAGAIN;
	}
}

static void put_chip(struct map_info *map, struct flchip *chip)
{
	if (chip->priv) {
		struct flchip_shared *shared = chip->priv;
		mutex_lock(&shared->lock);
		if (shared->writing == chip && chip->oldstate == FL_READY) {
			/* We own the ability to write, but we're done */
			shared->writing = shared->erasing;
			if (shared->writing && shared->writing != chip) {
				/* give back the ownership */
				struct flchip *loaner = shared->writing;
				mutex_lock(&loaner->mutex);
				mutex_unlock(&shared->lock);
				mutex_unlock(&chip->mutex);
				put_chip(map, loaner);
				mutex_lock(&chip->mutex);
				mutex_unlock(&loaner->mutex);
				wake_up(&chip->wq);
				return;
			}
			shared->erasing = NULL;
			shared->writing = NULL;
		} else if (shared->erasing == chip && shared->writing != chip) {
			/*
			 * We own the ability to erase without the ability
			 * to write, which means the erase was suspended
			 * and some other partition is currently writing.
			 * Don't let the switch below mess things up since
			 * we don't have ownership to resume anything.
			 */
			mutex_unlock(&shared->lock);
			wake_up(&chip->wq);
			return;
		}
		mutex_unlock(&shared->lock);
	}

	switch (chip->oldstate) {
	case FL_ERASING:
		map_write(map, CMD(LPDDR_RESUME),
				map->pfow_base + PFOW_COMMAND_CODE);
		map_write(map, CMD(LPDDR_START_EXECUTION),
				map->pfow_base + PFOW_COMMAND_EXECUTE);
		chip->oldstate = FL_READY;
		chip->state = FL_ERASING;
		break;
	case FL_READY:
		break;
	default:
		printk(KERN_ERR "%s: put_chip() called with oldstate %d!\n",
				map->name, chip->oldstate);
	}
	wake_up(&chip->wq);
}

int do_write_buffer(struct map_info *map, struct flchip *chip,
			unsigned long adr, const struct kvec **pvec,
			unsigned long *pvec_seek, int len)
{
	struct lpddr_private *lpddr = map->fldrv_priv;
	map_word datum;
	int ret, wbufsize, word_gap, words;
	const struct kvec *vec;
	unsigned long vec_seek;
	unsigned long prog_buf_ofs;

	wbufsize = 1 << lpddr->qinfo->BufSizeShift;

	mutex_lock(&chip->mutex);
	ret = get_chip(map, chip, FL_WRITING);
	if (ret) {
		mutex_unlock(&chip->mutex);
		return ret;
	}
	/* Figure out the number of words to write */
	word_gap = (-adr & (map_bankwidth(map)-1));
	words = (len - word_gap + map_bankwidth(map) - 1) / map_bankwidth(map);
	if (!word_gap) {
		words--;
	} else {
		word_gap = map_bankwidth(map) - word_gap;
		adr -= word_gap;
		datum = map_word_ff(map);
	}
	/* Write data */
	/* Get the program buffer offset from PFOW register data first*/
	prog_buf_ofs = map->pfow_base + CMDVAL(map_read(map,
				map->pfow_base + PFOW_PROGRAM_BUFFER_OFFSET));
	vec = *pvec;
	vec_seek = *pvec_seek;
	do {
		int n = map_bankwidth(map) - word_gap;

		if (n > vec->iov_len - vec_seek)
			n = vec->iov_len - vec_seek;
		if (n > len)
			n = len;

		if (!word_gap && (len < map_bankwidth(map)))
			datum = map_word_ff(map);

		datum = map_word_load_partial(map, datum,
				vec->iov_base + vec_seek, word_gap, n);

		len -= n;
		word_gap += n;
		if (!len || word_gap == map_bankwidth(map)) {
			map_write(map, datum, prog_buf_ofs);
			prog_buf_ofs += map_bankwidth(map);
			word_gap = 0;
		}

		vec_seek += n;
		if (vec_seek == vec->iov_len) {
			vec++;
			vec_seek = 0;
		}
	} while (len);
	*pvec = vec;
	*pvec_seek = vec_seek;

	/* GO GO GO */
	send_pfow_command(map, LPDDR_BUFF_PROGRAM, adr, wbufsize, NULL);
	chip->state = FL_WRITING;
	ret = wait_for_ready(map, chip, (1<<lpddr->qinfo->ProgBufferTime));
	if (ret)	{
		printk(KERN_WARNING"%s Buffer program error: %d at %lx; \n",
			map->name, ret, adr);
		goto out;
	}

 out:	put_chip(map, chip);
	mutex_unlock(&chip->mutex);
	return ret;
}

int do_erase_oneblock(struct mtd_info *mtd, loff_t adr)
{
	struct map_info *map = mtd->priv;
	struct lpddr_private *lpddr = map->fldrv_priv;
	int chipnum = adr >> lpddr->chipshift;
	struct flchip *chip = &lpddr->chips[chipnum];
	int ret;

	mutex_lock(&chip->mutex);
	ret = get_chip(map, chip, FL_ERASING);
	if (ret) {
		mutex_unlock(&chip->mutex);
		return ret;
	}
	send_pfow_command(map, LPDDR_BLOCK_ERASE, adr, 0, NULL);
	chip->state = FL_ERASING;
	ret = wait_for_ready(map, chip, (1<<lpddr->qinfo->BlockEraseTime)*1000);
	if (ret) {
		printk(KERN_WARNING"%s Erase block error %d at : %llx\n",
			map->name, ret, adr);
		goto out;
	}
 out:	put_chip(map, chip);
	mutex_unlock(&chip->mutex);
	return ret;
}

static int lpddr_read(struct mtd_info *mtd, loff_t adr, size_t len,
			size_t *retlen, u_char *buf)
{
	struct map_info *map = mtd->priv;
	struct lpddr_private *lpddr = map->fldrv_priv;
	int chipnum = adr >> lpddr->chipshift;
	struct flchip *chip = &lpddr->chips[chipnum];
	int ret = 0;

	mutex_lock(&chip->mutex);
	ret = get_chip(map, chip, FL_READY);
	if (ret) {
		mutex_unlock(&chip->mutex);
		return ret;
	}

	map_copy_from(map, buf, adr, len);
	*retlen = len;

	put_chip(map, chip);
	mutex_unlock(&chip->mutex);
	return ret;
}

static int lpddr_point(struct mtd_info *mtd, loff_t adr, size_t len,
			size_t *retlen, void **mtdbuf, resource_size_t *phys)
{
	struct map_info *map = mtd->priv;
	struct lpddr_private *lpddr = map->fldrv_priv;
	int chipnum = adr >> lpddr->chipshift;
	unsigned long ofs, last_end = 0;
	struct flchip *chip = &lpddr->chips[chipnum];
	int ret = 0;

	if (!map->virt)
		return -EINVAL;

	/* ofs: offset within the first chip that the first read should start */
	ofs = adr - (chipnum << lpddr->chipshift);
	*mtdbuf = (void *)map->virt + chip->start + ofs;

	while (len) {
		unsigned long thislen;

		if (chipnum >= lpddr->numchips)
			break;

		/* We cannot point across chips that are virtually disjoint */
		if (!last_end)
			last_end = chip->start;
		else if (chip->start != last_end)
			break;

		if ((len + ofs - 1) >> lpddr->chipshift)
			thislen = (1<<lpddr->chipshift) - ofs;
		else
			thislen = len;
		/* get the chip */
		mutex_lock(&chip->mutex);
		ret = get_chip(map, chip, FL_POINT);
		mutex_unlock(&chip->mutex);
		if (ret)
			break;

		chip->state = FL_POINT;
		chip->ref_point_counter++;
		*retlen += thislen;
		len -= thislen;

		ofs = 0;
		last_end += 1 << lpddr->chipshift;
		chipnum++;
		chip = &lpddr->chips[chipnum];
	}
	return 0;
}

static int lpddr_unpoint (struct mtd_info *mtd, loff_t adr, size_t len)
{
	struct map_info *map = mtd->priv;
	struct lpddr_private *lpddr = map->fldrv_priv;
	int chipnum = adr >> lpddr->chipshift, err = 0;
	unsigned long ofs;

	/* ofs: offset within the first chip that the first read should start */
	ofs = adr - (chipnum << lpddr->chipshift);

	while (len) {
		unsigned long thislen;
		struct flchip *chip;

		chip = &lpddr->chips[chipnum];
		if (chipnum >= lpddr->numchips)
			break;

		if ((len + ofs - 1) >> lpddr->chipshift)
			thislen = (1<<lpddr->chipshift) - ofs;
		else
			thislen = len;

		mutex_lock(&chip->mutex);
		if (chip->state == FL_POINT) {
			chip->ref_point_counter--;
			if (chip->ref_point_counter == 0)
				chip->state = FL_READY;
		} else {
			printk(KERN_WARNING "%s: Warning: unpoint called on non"
					"pointed region\n", map->name);
			err = -EINVAL;
		}

		put_chip(map, chip);
		mutex_unlock(&chip->mutex);

		len -= thislen;
		ofs = 0;
		chipnum++;
	}

	return err;
}

static int lpddr_write_buffers(struct mtd_info *mtd, loff_t to, size_t len,
				size_t *retlen, const u_char *buf)
{
	struct kvec vec;

	vec.iov_base = (void *) buf;
	vec.iov_len = len;

	return lpddr_writev(mtd, &vec, 1, to, retlen);
}


static int lpddr_writev(struct mtd_info *mtd, const struct kvec *vecs,
				unsigned long count, loff_t to, size_t *retlen)
{
	struct map_info *map = mtd->priv;
	struct lpddr_private *lpddr = map->fldrv_priv;
	int ret = 0;
	int chipnum;
	unsigned long ofs, vec_seek, i;
	int wbufsize = 1 << lpddr->qinfo->BufSizeShift;
	size_t len = 0;

	for (i = 0; i < count; i++)
		len += vecs[i].iov_len;

	if (!len)
		return 0;

	chipnum = to >> lpddr->chipshift;

	ofs = to;
	vec_seek = 0;

	do {
		/* We must not cross write block boundaries */
		int size = wbufsize - (ofs & (wbufsize-1));

		if (size > len)
			size = len;

		ret = do_write_buffer(map, &lpddr->chips[chipnum],
					  ofs, &vecs, &vec_seek, size);
		if (ret)
			return ret;

		ofs += size;
		(*retlen) += size;
		len -= size;

		/* Be nice and reschedule with the chip in a usable
		 * state for other processes */
		cond_resched();

	} while (len);

	return 0;
}

static int lpddr_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	unsigned long ofs, len;
	int ret;
	struct map_info *map = mtd->priv;
	struct lpddr_private *lpddr = map->fldrv_priv;
	int size = 1 << lpddr->qinfo->UniformBlockSizeShift;

	ofs = instr->addr;
	len = instr->len;

	while (len > 0) {
		ret = do_erase_oneblock(mtd, ofs);
		if (ret)
			return ret;
		ofs += size;
		len -= size;
	}
	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);

	return 0;
}

#define DO_XXLOCK_LOCK		1
#define DO_XXLOCK_UNLOCK	2
int do_xxlock(struct mtd_info *mtd, loff_t adr, uint32_t len, int thunk)
{
	int ret = 0;
	struct map_info *map = mtd->priv;
	struct lpddr_private *lpddr = map->fldrv_priv;
	int chipnum = adr >> lpddr->chipshift;
	struct flchip *chip = &lpddr->chips[chipnum];

	mutex_lock(&chip->mutex);
	ret = get_chip(map, chip, FL_LOCKING);
	if (ret) {
		mutex_unlock(&chip->mutex);
		return ret;
	}

	if (thunk == DO_XXLOCK_LOCK) {
		send_pfow_command(map, LPDDR_LOCK_BLOCK, adr, adr + len, NULL);
		chip->state = FL_LOCKING;
	} else if (thunk == DO_XXLOCK_UNLOCK) {
		send_pfow_command(map, LPDDR_UNLOCK_BLOCK, adr, adr + len, NULL);
		chip->state = FL_UNLOCKING;
	} else
		BUG();

	ret = wait_for_ready(map, chip, 1);
	if (ret)	{
		printk(KERN_ERR "%s: block unlock error status %d \n",
				map->name, ret);
		goto out;
	}
out:	put_chip(map, chip);
	mutex_unlock(&chip->mutex);
	return ret;
}

static int lpddr_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	return do_xxlock(mtd, ofs, len, DO_XXLOCK_LOCK);
}

static int lpddr_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	return do_xxlock(mtd, ofs, len, DO_XXLOCK_UNLOCK);
}

int word_program(struct map_info *map, loff_t adr, uint32_t curval)
{
    int ret;
	struct lpddr_private *lpddr = map->fldrv_priv;
	int chipnum = adr >> lpddr->chipshift;
	struct flchip *chip = &lpddr->chips[chipnum];

	mutex_lock(&chip->mutex);
	ret = get_chip(map, chip, FL_WRITING);
	if (ret) {
		mutex_unlock(&chip->mutex);
		return ret;
	}

	send_pfow_command(map, LPDDR_WORD_PROGRAM, adr, 0x00, (map_word *)&curval);

	ret = wait_for_ready(map, chip, (1<<lpddr->qinfo->SingleWordProgTime));
	if (ret)	{
		printk(KERN_WARNING"%s word_program error at: %llx; val: %x\n",
			map->name, adr, curval);
		goto out;
	}

out:	put_chip(map, chip);
	mutex_unlock(&chip->mutex);
	return ret;
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexey Korolev <akorolev@infradead.org>");
MODULE_DESCRIPTION("MTD driver for LPDDR flash chips");
l.org> 2005-04-16 18:20:36 -0400 committer Linus Torvalds <torvalds@ppc970.osdl.org> 2005-04-16 18:20:36 -0400 Linux-2.6.12-rc2' href='/cgit/cgit.cgi/litmus-rt.git/commit/drivers/char/mem.c?id=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2'>1da177e4c3f4
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/*
 *  linux/drivers/char/mem.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Added devfs support.
 *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
 *  Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
 */

#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/raw.h>
#include <linux/tty.h>
#include <linux/capability.h>
#include <linux/ptrace.h>
#include <linux/device.h>
#include <linux/highmem.h>
#include <linux/backing-dev.h>
#include <linux/splice.h>
#include <linux/pfn.h>
#include <linux/export.h>
#include <linux/io.h>
#include <linux/aio.h>

#include <asm/uaccess.h>

#ifdef CONFIG_IA64
# include <linux/efi.h>
#endif

#define DEVPORT_MINOR	4

static inline unsigned long size_inside_page(unsigned long start,
					     unsigned long size)
{
	unsigned long sz;

	sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));

	return min(sz, size);
}

#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
{
	return addr + count <= __pa(high_memory);
}

static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
{
	return 1;
}
#endif

#ifdef CONFIG_STRICT_DEVMEM
static inline int range_is_allowed(unsigned long pfn, unsigned long size)
{
	u64 from = ((u64)pfn) << PAGE_SHIFT;
	u64 to = from + size;
	u64 cursor = from;

	while (cursor < to) {
		if (!devmem_is_allowed(pfn)) {
			printk(KERN_INFO
		"Program %s tried to access /dev/mem between %Lx->%Lx.\n",
				current->comm, from, to);
			return 0;
		}
		cursor += PAGE_SIZE;
		pfn++;
	}
	return 1;
}
#else
static inline int range_is_allowed(unsigned long pfn, unsigned long size)
{
	return 1;
}
#endif

void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr)
{
}

/*
 * This funcion reads the *physical* memory. The f_pos points directly to the
 * memory location.
 */
static ssize_t read_mem(struct file *file, char __user *buf,
			size_t count, loff_t *ppos)
{
	phys_addr_t p = *ppos;
	ssize_t read, sz;
	char *ptr;

	if (p != *ppos)
		return 0;

	if (!valid_phys_addr_range(p, count))
		return -EFAULT;
	read = 0;
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
	/* we don't have page 0 mapped on sparc and m68k.. */
	if (p < PAGE_SIZE) {
		sz = size_inside_page(p, count);
		if (sz > 0) {
			if (clear_user(buf, sz))
				return -EFAULT;
			buf += sz;
			p += sz;
			count -= sz;
			read += sz;
		}
	}
#endif

	while (count > 0) {
		unsigned long remaining;

		sz = size_inside_page(p, count);

		if (!range_is_allowed(p >> PAGE_SHIFT, count))
			return -EPERM;

		/*
		 * On ia64 if a page has been mapped somewhere as uncached, then
		 * it must also be accessed uncached by the kernel or data
		 * corruption may occur.
		 */
		ptr = xlate_dev_mem_ptr(p);
		if (!ptr)
			return -EFAULT;

		remaining = copy_to_user(buf, ptr, sz);
		unxlate_dev_mem_ptr(p, ptr);
		if (remaining)
			return -EFAULT;

		buf += sz;
		p += sz;
		count -= sz;
		read += sz;
	}

	*ppos += read;
	return read;
}

static ssize_t write_mem(struct file *file, const char __user *buf,
			 size_t count, loff_t *ppos)
{
	phys_addr_t p = *ppos;
	ssize_t written, sz;
	unsigned long copied;
	void *ptr;

	if (p != *ppos)
		return -EFBIG;

	if (!valid_phys_addr_range(p, count))
		return -EFAULT;

	written = 0;

#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
	/* we don't have page 0 mapped on sparc and m68k.. */
	if (p < PAGE_SIZE) {
		sz = size_inside_page(p, count);
		/* Hmm. Do something? */
		buf += sz;
		p += sz;
		count -= sz;
		written += sz;
	}
#endif

	while (count > 0) {
		sz = size_inside_page(p, count);

		if (!range_is_allowed(p >> PAGE_SHIFT, sz))
			return -EPERM;

		/*
		 * On ia64 if a page has been mapped somewhere as uncached, then
		 * it must also be accessed uncached by the kernel or data
		 * corruption may occur.
		 */
		ptr = xlate_dev_mem_ptr(p);
		if (!ptr) {
			if (written)
				break;
			return -EFAULT;
		}

		copied = copy_from_user(ptr, buf, sz);
		unxlate_dev_mem_ptr(p, ptr);
		if (copied) {
			written += sz - copied;
			if (written)
				break;
			return -EFAULT;
		}

		buf += sz;
		p += sz;
		count -= sz;
		written += sz;
	}

	*ppos += written;
	return written;
}

int __weak phys_mem_access_prot_allowed(struct file *file,
	unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
{
	return 1;
}

#ifndef __HAVE_PHYS_MEM_ACCESS_PROT

/*
 * Architectures vary in how they handle caching for addresses
 * outside of main memory.
 *
 */
#ifdef pgprot_noncached
static int uncached_access(struct file *file, phys_addr_t addr)
{
#if defined(CONFIG_IA64)
	/*
	 * On ia64, we ignore O_DSYNC because we cannot tolerate memory
	 * attribute aliases.
	 */
	return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
#elif defined(CONFIG_MIPS)
	{
		extern int __uncached_access(struct file *file,
					     unsigned long addr);

		return __uncached_access(file, addr);
	}
#else
	/*
	 * Accessing memory above the top the kernel knows about or through a
	 * file pointer
	 * that was marked O_DSYNC will be done non-cached.
	 */
	if (file->f_flags & O_DSYNC)
		return 1;
	return addr >= __pa(high_memory);
#endif
}
#endif

static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
				     unsigned long size, pgprot_t vma_prot)
{
#ifdef pgprot_noncached
	phys_addr_t offset = pfn << PAGE_SHIFT;

	if (uncached_access(file, offset))
		return pgprot_noncached(vma_prot);
#endif
	return vma_prot;
}
#endif

#ifndef CONFIG_MMU
static unsigned long get_unmapped_area_mem(struct file *file,
					   unsigned long addr,
					   unsigned long len,
					   unsigned long pgoff,
					   unsigned long flags)
{
	if (!valid_mmap_phys_addr_range(pgoff, len))
		return (unsigned long) -EINVAL;
	return pgoff << PAGE_SHIFT;
}

/* can't do an in-place private mapping if there's no MMU */
static inline int private_mapping_ok(struct vm_area_struct *vma)
{
	return vma->vm_flags & VM_MAYSHARE;
}
#else
#define get_unmapped_area_mem	NULL

static inline int private_mapping_ok(struct vm_area_struct *vma)
{
	return 1;
}
#endif

static const struct vm_operations_struct mmap_mem_ops = {
#ifdef CONFIG_HAVE_IOREMAP_PROT
	.access = generic_access_phys
#endif
};

static int mmap_mem(struct file *file, struct vm_area_struct *vma)
{
	size_t size = vma->vm_end - vma->vm_start;

	if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
		return -EINVAL;

	if (!private_mapping_ok(vma))
		return -ENOSYS;

	if (!range_is_allowed(vma->vm_pgoff, size))
		return -EPERM;

	if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
						&vma->vm_page_prot))
		return -EINVAL;

	vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
						 size,
						 vma->vm_page_prot);

	vma->vm_ops = &mmap_mem_ops;

	/* Remap-pfn-range will mark the range VM_IO */
	if (remap_pfn_range(vma,
			    vma->vm_start,
			    vma->vm_pgoff,
			    size,
			    vma->vm_page_prot)) {
		return -EAGAIN;
	}
	return 0;
}

#ifdef CONFIG_DEVKMEM
static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
{
	unsigned long pfn;

	/* Turn a kernel-virtual address into a physical page frame */
	pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;

	/*
	 * RED-PEN: on some architectures there is more mapped memory than
	 * available in mem_map which pfn_valid checks for. Perhaps should add a
	 * new macro here.
	 *
	 * RED-PEN: vmalloc is not supported right now.
	 */
	if (!pfn_valid(pfn))
		return -EIO;

	vma->vm_pgoff = pfn;
	return mmap_mem(file, vma);
}
#endif

#ifdef CONFIG_DEVKMEM
/*
 * This function reads the *virtual* memory as seen by the kernel.
 */
static ssize_t read_kmem(struct file *file, char __user *buf,
			 size_t count, loff_t *ppos)
{
	unsigned long p = *ppos;
	ssize_t low_count, read, sz;
	char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
	int err = 0;

	read = 0;
	if (p < (unsigned long) high_memory) {
		low_count = count;
		if (count > (unsigned long)high_memory - p)
			low_count = (unsigned long)high_memory - p;

#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
		/* we don't have page 0 mapped on sparc and m68k.. */
		if (p < PAGE_SIZE && low_count > 0) {
			sz = size_inside_page(p, low_count);
			if (clear_user(buf, sz))
				return -EFAULT;
			buf += sz;
			p += sz;
			read += sz;
			low_count -= sz;
			count -= sz;
		}
#endif
		while (low_count > 0) {
			sz = size_inside_page(p, low_count);

			/*
			 * On ia64 if a page has been mapped somewhere as
			 * uncached, then it must also be accessed uncached
			 * by the kernel or data corruption may occur
			 */
			kbuf = xlate_dev_kmem_ptr((char *)p);

			if (copy_to_user(buf, kbuf, sz))
				return -EFAULT;
			buf += sz;
			p += sz;
			read += sz;
			low_count -= sz;
			count -= sz;
		}
	}

	if (count > 0) {
		kbuf = (char *)__get_free_page(GFP_KERNEL);
		if (!kbuf)
			return -ENOMEM;
		while (count > 0) {
			sz = size_inside_page(p, count);
			if (!is_vmalloc_or_module_addr((void *)p)) {
				err = -ENXIO;
				break;
			}
			sz = vread(kbuf, (char *)p, sz);
			if (!sz)
				break;
			if (copy_to_user(buf, kbuf, sz)) {
				err = -EFAULT;
				break;
			}
			count -= sz;
			buf += sz;
			read += sz;
			p += sz;
		}
		free_page((unsigned long)kbuf);
	}
	*ppos = p;
	return read ? read : err;
}


static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
				size_t count, loff_t *ppos)
{
	ssize_t written, sz;
	unsigned long copied;

	written = 0;
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
	/* we don't have page 0 mapped on sparc and m68k.. */
	if (p < PAGE_SIZE) {
		sz = size_inside_page(p, count);
		/* Hmm. Do something? */
		buf += sz;
		p += sz;
		count -= sz;
		written += sz;
	}
#endif

	while (count > 0) {
		char *ptr;

		sz = size_inside_page(p, count);

		/*
		 * On ia64 if a page has been mapped somewhere as uncached, then
		 * it must also be accessed uncached by the kernel or data
		 * corruption may occur.
		 */
		ptr = xlate_dev_kmem_ptr((char *)p);

		copied = copy_from_user(ptr, buf, sz);
		if (copied) {
			written += sz - copied;
			if (written)
				break;
			return -EFAULT;
		}
		buf += sz;
		p += sz;
		count -= sz;
		written += sz;
	}

	*ppos += written;
	return written;
}

/*
 * This function writes to the *virtual* memory as seen by the kernel.
 */
static ssize_t write_kmem(struct file *file, const char __user *buf,
			  size_t count, loff_t *ppos)
{
	unsigned long p = *ppos;
	ssize_t wrote = 0;
	ssize_t virtr = 0;
	char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
	int err = 0;

	if (p < (unsigned long) high_memory) {
		unsigned long to_write = min_t(unsigned long, count,
					       (unsigned long)high_memory - p);
		wrote = do_write_kmem(p, buf, to_write, ppos);
		if (wrote != to_write)
			return wrote;
		p += wrote;
		buf += wrote;
		count -= wrote;
	}

	if (count > 0) {
		kbuf = (char *)__get_free_page(GFP_KERNEL);
		if (!kbuf)
			return wrote ? wrote : -ENOMEM;
		while (count > 0) {
			unsigned long sz = size_inside_page(p, count);
			unsigned long n;

			if (!is_vmalloc_or_module_addr((void *)p)) {
				err = -ENXIO;
				break;
			}
			n = copy_from_user(kbuf, buf, sz);
			if (n) {
				err = -EFAULT;
				break;
			}
			vwrite(kbuf, (char *)p, sz);
			count -= sz;
			buf += sz;
			virtr += sz;
			p += sz;
		}
		free_page((unsigned long)kbuf);
	}

	*ppos = p;
	return virtr + wrote ? : err;
}
#endif

#ifdef CONFIG_DEVPORT
static ssize_t read_port(struct file *file, char __user *buf,
			 size_t count, loff_t *ppos)
{
	unsigned long i = *ppos;
	char __user *tmp = buf;

	if (!access_ok(VERIFY_WRITE, buf, count))
		return -EFAULT;
	while (count-- > 0 && i < 65536) {
		if (__put_user(inb(i), tmp) < 0)
			return -EFAULT;
		i++;
		tmp++;
	}
	*ppos = i;
	return tmp-buf;
}

static ssize_t write_port(struct file *file, const char __user *buf,
			  size_t count, loff_t *ppos)
{
	unsigned long i = *ppos;
	const char __user *tmp = buf;

	if (!access_ok(VERIFY_READ, buf, count))
		return -EFAULT;
	while (count-- > 0 && i < 65536) {
		char c;
		if (__get_user(c, tmp)) {
			if (tmp > buf)
				break;
			return -EFAULT;
		}
		outb(c, i);
		i++;
		tmp++;
	}
	*ppos = i;
	return tmp-buf;
}
#endif

static ssize_t read_null(struct file *file, char __user *buf,
			 size_t count, loff_t *ppos)
{
	return 0;
}

static ssize_t write_null(struct file *file, const char __user *buf,
			  size_t count, loff_t *ppos)
{
	return count;
}

static ssize_t aio_read_null(struct kiocb *iocb, const struct iovec *iov,
			     unsigned long nr_segs, loff_t pos)
{
	return 0;
}

static ssize_t aio_write_null(struct kiocb *iocb, const struct iovec *iov,
			      unsigned long nr_segs, loff_t pos)
{
	return iov_length(iov, nr_segs);
}

static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
			struct splice_desc *sd)
{
	return sd->len;
}

static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
				 loff_t *ppos, size_t len, unsigned int flags)
{
	return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
}

static ssize_t read_zero(struct file *file, char __user *buf,
			 size_t count, loff_t *ppos)
{
	size_t written;

	if (!count)
		return 0;

	if (!access_ok(VERIFY_WRITE, buf, count))
		return -EFAULT;

	written = 0;
	while (count) {
		unsigned long unwritten;
		size_t chunk = count;

		if (chunk > PAGE_SIZE)
			chunk = PAGE_SIZE;	/* Just for latency reasons */
		unwritten = __clear_user(buf, chunk);
		written += chunk - unwritten;
		if (unwritten)
			break;
		if (signal_pending(current))
			return written ? written : -ERESTARTSYS;
		buf += chunk;
		count -= chunk;
		cond_resched();
	}
	return written ? written : -EFAULT;
}

static ssize_t aio_read_zero(struct kiocb *iocb, const struct iovec *iov,
			     unsigned long nr_segs, loff_t pos)
{
	size_t written = 0;
	unsigned long i;
	ssize_t ret;

	for (i = 0; i < nr_segs; i++) {
		ret = read_zero(iocb->ki_filp, iov[i].iov_base, iov[i].iov_len,
				&pos);
		if (ret < 0)
			break;
		written += ret;
	}

	return written ? written : -EFAULT;
}

static int mmap_zero(struct file *file, struct vm_area_struct *vma)
{
#ifndef CONFIG_MMU
	return -ENOSYS;
#endif
	if (vma->vm_flags & VM_SHARED)
		return shmem_zero_setup(vma);
	return 0;
}

static ssize_t write_full(struct file *file, const char __user *buf,
			  size_t count, loff_t *ppos)
{
	return -ENOSPC;
}

/*
 * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 * can fopen() both devices with "a" now.  This was previously impossible.
 * -- SRB.
 */
static loff_t null_lseek(struct file *file, loff_t offset, int orig)
{
	return file->f_pos = 0;
}

/*
 * The memory devices use the full 32/64 bits of the offset, and so we cannot
 * check against negative addresses: they are ok. The return value is weird,
 * though, in that case (0).
 *
 * also note that seeking relative to the "end of file" isn't supported:
 * it has no meaning, so it returns -EINVAL.
 */
static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
{
	loff_t ret;

	mutex_lock(&file_inode(file)->i_mutex);
	switch (orig) {
	case SEEK_CUR:
		offset += file->f_pos;
	case SEEK_SET:
		/* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
		if (IS_ERR_VALUE((unsigned long long)offset)) {
			ret = -EOVERFLOW;
			break;
		}
		file->f_pos = offset;
		ret = file->f_pos;
		force_successful_syscall_return();
		break;
	default:
		ret = -EINVAL;
	}
	mutex_unlock(&file_inode(file)->i_mutex);
	return ret;
}

static int open_port(struct inode *inode, struct file *filp)
{
	return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}

#define zero_lseek	null_lseek
#define full_lseek      null_lseek
#define write_zero	write_null
#define read_full       read_zero
#define aio_write_zero	aio_write_null
#define open_mem	open_port
#define open_kmem	open_mem

static const struct file_operations mem_fops = {
	.llseek		= memory_lseek,
	.read		= read_mem,
	.write		= write_mem,
	.mmap		= mmap_mem,
	.open		= open_mem,
	.get_unmapped_area = get_unmapped_area_mem,
};

#ifdef CONFIG_DEVKMEM
static const struct file_operations kmem_fops = {
	.llseek		= memory_lseek,
	.read		= read_kmem,
	.write		= write_kmem,
	.mmap		= mmap_kmem,
	.open		= open_kmem,
	.get_unmapped_area = get_unmapped_area_mem,
};
#endif

static const struct file_operations null_fops = {
	.llseek		= null_lseek,
	.read		= read_null,
	.write		= write_null,
	.aio_read	= aio_read_null,
	.aio_write	= aio_write_null,
	.splice_write	= splice_write_null,
};

#ifdef CONFIG_DEVPORT
static const struct file_operations port_fops = {
	.llseek		= memory_lseek,
	.read		= read_port,
	.write		= write_port,
	.open		= open_port,
};
#endif

static const struct file_operations zero_fops = {
	.llseek		= zero_lseek,
	.read		= read_zero,
	.write		= write_zero,
	.aio_read	= aio_read_zero,
	.aio_write	= aio_write_zero,
	.mmap		= mmap_zero,
};

/*
 * capabilities for /dev/zero
 * - permits private mappings, "copies" are taken of the source of zeros
 * - no writeback happens
 */
static struct backing_dev_info zero_bdi = {
	.name		= "char/mem",
	.capabilities	= BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK,
};

static const struct file_operations full_fops = {
	.llseek		= full_lseek,
	.read		= read_full,
	.write		= write_full,
};

static const struct memdev {
	const char *name;
	umode_t mode;
	const struct file_operations *fops;
	struct backing_dev_info *dev_info;
} devlist[] = {
	 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
#ifdef CONFIG_DEVKMEM
	 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
#endif
	 [3] = { "null", 0666, &null_fops, NULL },
#ifdef CONFIG_DEVPORT
	 [4] = { "port", 0, &port_fops, NULL },
#endif
	 [5] = { "zero", 0666, &zero_fops, &zero_bdi },
	 [7] = { "full", 0666, &full_fops, NULL },
	 [8] = { "random", 0666, &random_fops, NULL },
	 [9] = { "urandom", 0666, &urandom_fops, NULL },
#ifdef CONFIG_PRINTK
	[11] = { "kmsg", 0644, &kmsg_fops, NULL },
#endif
};

static int memory_open(struct inode *inode, struct file *filp)
{
	int minor;
	const struct memdev *dev;

	minor = iminor(inode);
	if (minor >= ARRAY_SIZE(devlist))
		return -ENXIO;

	dev = &devlist[minor];
	if (!dev->fops)
		return -ENXIO;

	filp->f_op = dev->fops;
	if (dev->dev_info)
		filp->f_mapping->backing_dev_info = dev->dev_info;

	/* Is /dev/mem or /dev/kmem ? */
	if (dev->dev_info == &directly_mappable_cdev_bdi)
		filp->f_mode |= FMODE_UNSIGNED_OFFSET;

	if (dev->fops->open)
		return dev->fops->open(inode, filp);

	return 0;
}

static const struct file_operations memory_fops = {
	.open = memory_open,
	.llseek = noop_llseek,
};

static char *mem_devnode(struct device *dev, umode_t *mode)
{
	if (mode && devlist[MINOR(dev->devt)].mode)
		*mode = devlist[MINOR(dev->devt)].mode;
	return NULL;
}

static struct class *mem_class;

static int __init chr_dev_init(void)
{
	int minor;
	int err;

	err = bdi_init(&zero_bdi);
	if (err)
		return err;

	if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
		printk("unable to get major %d for memory devs\n", MEM_MAJOR);

	mem_class = class_create(THIS_MODULE, "mem");
	if (IS_ERR(mem_class))
		return PTR_ERR(mem_class);

	mem_class->devnode = mem_devnode;
	for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
		if (!devlist[minor].name)
			continue;

		/*
		 * Create /dev/port?
		 */
		if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
			continue;

		device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
			      NULL, devlist[minor].name);
	}

	return tty_init();
}

fs_initcall(chr_dev_init);